Very Good Question.
Not many explains why, but accept it as what it is. So thus most of the house inspectors do.
If I remove the plate of a wall outlet, and touch the hot screw, I’ll get a shock.
As you would agree, when you touch HOT, the current flows from hot to the GROUND through your body. When your body is floating, HOT does not get you a shock. You would be shocked when you see some people intentionally touch HOT and not getting shocked. That is one way to view a lineman can handles high power live lines.
The potential difference with the ground is enough to send some current into my hand. Importantly, this happens even if I didn’t disconnect the neutral, which has much lower resistance.
So, by the same logic, why isn’t there current flowing down into the grounding rod of my house?
Never try this: If you remove the jumper between the NEUTRAL and the GROUND at the service entrance point, HOT & GROUND/GROUNDING-ROD will supply power, though the voltage and amperage are questionable. Go far back to when my town just got electricity, kids found free electricity, bypassing the meter (those days meter), by taking HOT and something plugged in the dirt, stronger than the HOT and NEUTRAL. We played melting and bending glass pieces using arc generated with lead from pencil. h h..
So, for an example, the current flows to the grounding rod, and get onto another grounding rod nearby then returns to the NEUTRAL. Not only that, it might find higher potential circuit around. GROUNDING points are everywhere, not only at the service drop.
The neutral and ground buses are jumpered at my panel. To the electricity flowing down the neutral at my panel, why isn’t the path to ground offered by the grounding rod at least as “attractive” as the path offered by my body was to the electricity in the outlet?
Yes, as you said, "people said that this is because the earth has much more resistance than the neutral", is one reason why. The resistance means loss and potential difference. Meantime, the GROUND, earth-ground through the grounding rod, is not a single current path for your service/circuit. Many artificial and natural sources, and loads, are on the ground (multiple circuits). Thus many factors are unpredictable.
Why GROUND WIRE (not the earth ground or grounding rod) is not offered as mains.
Ground wire (green wire) is for SAFETY (discussed down there). Current flow through ground is GROUND FAULT, detected and interrupted by GFC, if you have any. GFC monitors if any current flows other than HOT and NEUTRAL, the source and return. So, GFC finds someone got attracted by the beauty of grounding rod, and prevents abusing it.
Your question, now, is:
Why is the grounding rod and the jumper needed?
Why the GROUND-ROD/GROUNDING is needed at all. How is it safe?
If the power plant, or the the distribution transformer at the service drop, had NEUTRAL to the EARTH-GROUND connection already, do we still need grounding rod?
The answer is:
However amount it can be, "current flow" occurs due to potential difference, and the flowing current develops potential difference.
-. When you touch the line, your body potential is REFERENCED on the GROUND (floor, earth ground). If you get electrocuted from hair dryer in the tub, GFC quickly determine you are in danger, since it detected the current flew from HOT to other than the NEUTRAL.
-. If the line gets floated (the NEUTRAL does not get GROUNDED), then the line can be at any potential from the GROUND. That can be really dangerous. Meantime, if you have your own circuit after isolated, like a transformer, generator, solar panel and etc. you still need put that to be based on the GROUND by connecting/coupling (phase isolation) it to the earth ground.
-. The potential develops along the transmission line. Thus, even if the NEUTRAL at source side was grounded, the NEUTRAL at service drop is (possibly) not at ground level. It needs assurance by grounding again at the service drop.
-. If the ground wire takes current (share the return current with NEUTRAL) then the GROUND is not the same potential level as the earth-ground, where your safety is referencing.
-. If the ground wire (that one with ground-rode) shares the return current, without GFC, and gets interrupted (cut off), the current finds undesirable path, like kitchen sink, or even can heat up to fire.
Meantime, utilities and electrical/electronic equipment can leak current, due to imperfect dielectric, or possibly EMI (not the radio frequency), to any exposed electrically conducting surface. When the ground wire is connected, the leakage can be taken to the ground, not to human. That is the purpose of the ground wire attached to washer/dryer and ovens.